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Active camouflage
molluscs such as this Cuttlefish can change color rapidly for signalling or to match their background]] Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal . In theory, active camouflage could provide perfect concealment from visual detection. Active camouflage is used in several groups of animals, including reptiles on land, and cephalopod molluscs and flatfish in the sea. Animals achieve active camouflage both by color change and (among marine animals) by counterillumination. In military usage, active camouflage remains at the research stage. Counterillumination camouflage was first investigated during the Second World War for marine use. Current research aims to achieve crypsis by using cameras to sense the visible background, and by controlling panels or coatings that can vary their appearance. Definition Active camouflage provides concealment in two ways: * by making an object not merely generally similar to its surroundings, but effectively invisible through accurate mimicry, and * by changing the appearance of the object as changes occur in its background. In animals Bothus ocellatus can change its color to match its background in a few seconds]] Active camouflage is present in several groups of animals including cephalopod molluscs, fish, and reptiles. There are two mechanisms of active camouflage in animals: counterillumination camouflage, and color change. Counterillumination camouflage is the production of light to blend in against a lit background. In the sea, light comes down from the surface, so when marine animals are seen from below, they appear darker than the background. Some species of cephalopod, such as the Midwater Squid and the Sparkling Enope Squid, produce light in photophores on their undersides to match the background. Bioluminescence is common among marine animals, so counterillumination camouflage may be widespread, though light has other functions, including attracting prey and signalling. Color change permits camouflage against different backgrounds. Many cephalopods including octopus, cuttlefish, and squid, and some terrestrial reptiles including chameleons and anoles can rapidly change color and pattern, though the major reasons for this include signalling, not only camouflage.Forbes, Peter. Dazzled and Deceived: Mimicry and Camouflage. Yale, 2009. Active camouflage is also used by many bottom-living flatfish such as plaice, sole, and flounder that actively copy the patterns and colors of the seafloor below them. For example, the tropical flounder Bothus ocellatus can match its pattern to "a wide range of background textures" in 2–8 seconds. See also References Bibliography * Burr, E. Godfrey. Illumination for Concealment of Ships at Night. Transactions of the Royal Society of Canada Third series, volume XLI, May 1947, pages 45–54. * George R. Lindsey. (Editor) No Day Long Enough: Canadian Science in World War II. (Toronto: Canadian Institute of Strategic Studies, 1997), pages 172-173. * Summary Technical Report of Division 16, NDRC. Volume 2: Visibility Studies and Some Applications in the Field of Camouflage. (Washington, D.C.: Office of Scientific Research and Development, National Defense Research Committee, 1946), pages 14–16 and 225-241. August 2, 1960. * Waddington, C.H. O.R. in World War 2: Operational Research Against the U-Boat. (London: Elek Science, 1973), pages 164-167. External links * "Multi-perspective background simulation cloaking process and apparatus", United States Patent & Trademark Office * "Now you see it, now you won't: Boeing lifts the veil on stealthy Bird of Prey", Jane's International Defence Review article mentioning Bird of Prey's daylight stealth capability * "Scientist show off 'invisible coat'", The Sydney Morning Herald, March 30, 2003 * Optical Camouflage * Phased Array Optics * "Thermal and Visual Camouflage System Patent No 6,338,292", United States Patent & Trademark Office * "Car that utilizes visual camouflage to change its color" Category:Military camouflage Category:Military electronics Category:Camouflage